At his first news conference since replacing Leon Panetta as Pentagon chief, Hagel struck a more relaxed tone about the budget reductions, part of $85 billion in government-wide spending cuts that were taking effect Friday at midnight.

Whereas Panetta had warned of "catastrophic" effects that could reduce America to the status of a "second-rate" military power, Hagel said he believed the across-the-board budget cuts and their far-reaching effects will prove manageable.

"Today, America has the best fighting force in the world capable of responding to any challenge," he told reporters. "This unnecessary budget crisis makes that job much harder. But we will continue to ensure America's security."

Hagel met for a little over an hour with the chiefs of each of the services, plus the chairman of the Joint Chiefs, Gen. Martin Dempsey, to discuss budget issues.

Hagel told reporters that numerous actions will be taken in coming days by the Army, Navy, Air Force and Marine Corps to begin meeting the requirement for $46 billion in budget savings by the end of the fiscal year on Sept. 30. He said thousands of defense civilian workers, for example, will be notified later this month that they could be required to take one day of unpaid leave per week through September.

President Barack Obama has exempted military personnel from the automatic budget cuts, and the Pentagon has decided that its combat operations in Afghanistan, as well as its nuclear weapons force, will be protected from reductions. Even so, the Army will curtail training of forces other than those scheduled to go to Afghanistan; the Air Force will reduce flying hours for pilots and the Navy has already announced plans to delay ship deployments and ship maintenance.

Ashton Carter, the deputy defense secretary, said the Pentagon is doing all it can to prevent a drastic curtailment of troop training. But he said that will prove harder if the administration and the Congress are unable to strike a budget deal soon.

"(For) those who do not appreciate how serious this is, as the year goes on, it will be unmistakable," Carter said. "This is not subtle."

The defense spending cuts will hit some states harder than others.

Carter sent warning letters to the governors of 10 states that will be most severely impacted: Virginia, Texas, Pennsylvania, Georgia, Florida, California, Maryland, Ohio, Alabama and Washington.

The letters lay out in stark terms the number of civilian defense workers in each state who will face unpaid furloughs and the cutbacks that will hurt local bases and defense contractors. Copies of the letters were provided to The Associated Press on Friday.